Sensitizing dyestuffs and dyestuff intermediates



Patented Feb. 5, 1946 UNITED STATES PAT NT SENSITIZING DYESTUFFSannnrns'rur'r INTERMEDIATES 'John David Kendall and Douglas JamesIlford, England, asslgnors to Ilford Limite I Ilford, England, a Britishcompany No Drawing. Application August 21, 1941, Serial 1:6):o 407,839.In Great Britain October 16,

This invention relates to the production of dyestuif intermediates andvto the production therefrom of dyestuifscapable of sensitisinggelatinosilver halide photographic emulsions. 1

According to this invention, dyestuif intermediates are producedby'reacting a heterocyclic nitrogen compound of the general formula:

The heterocyclic nitrogen compound employed may be any ofthose commonlyemployed in the manufacture of cyanlne dyes. Typical examples are setforth hereinafter. The ortho-ester may be, for example, an ester. of'ortho-acetic acid. ortho-proplonic acid or ortho-benzoic acid.Preferably an ethyl ortho ester is employed though other alkylorthoeste'rs or aryl or aralkyl orthoesters may be employed, if desired.1

According to a further feature of the invention, dyestufis are producedby condensing an alkyl or. aralkyl quaternary salt of a dyestuifintermediate of the general Formula HI with an alkyl or aralkylquaternary salt of a heterocyclic nitrogen compound containing anexternal reactive methyl, m'onosubstituted methyl, or amino group in theaor 'y-position to the heterocyclic nitrogen atom or with acorresponding 'heterocyclic nitrogen base obtainable by the eliminationof a hydrogen atom and the acid residue from such quaternary salt;

The course of this reaction may be illustrated asfollows, where aheterocyclic nitrogen compound containing an external reactive meth l ormono-substituted methyl group is employed:

Where the corresponding heterocyclic nitrogen base is employed, thereaction proceeds s ilarly but the groups H and Y are not present sothat the acid HY is. not eliminated. Where the heterocyclic compoundcontains a reactive amino group,

the two hydrogen atoms of such amino group are eliminated as R203 and-HY leaving a nitrogen atom instead of the group of Formula IV. 1

Although it is indicated above that the acid HY is eliminated in thereaction it is to be appreciated that in some cases the acid HX iseliminated. In all compounds of this general type the position of theacid residue X or Y is in doubt and -.it possibly resonates between thetwo quaternary nitrogen atoms. v

In the foregoing formulae, the groups D and D2 are the residues ofheterocyclic nuclei, e. g. 40 residues of the nuclei of substituted orunsubstituted thiazoles, thiazolines, oxazoles, oxazolines, selenazoles,selenazolines, pyridine, quinoline, indolenine, diazines (e. g.pyrimidine) thio-diazoles and quinazoline and the correspondingsubstituted or unsubstituted polycyclic compounds such as benzthiazoles,naphthathiazoles and anthrath'iazolea, and also the diazines vdescribedin.

British specification No. 425,609. V

The groups R1, Ra, Ra, R4, and Ramay be alkyl or aralkyl groups;examples aremeth'yl, ethyl, propyl, butyl and higher alkyl groups, andbenzyl and naphthyl-methyl groups. The groups R1, R: and Rrmay the am:groups, andy'examples are phenyl and naphthyl-groups. Such aryl' groupsmay t emselves be substituted, e. g by alkyi,

amino. hydroxy, alkoxy and oxyalkyl roups and by halogen atoms. Thegroup B: may be a hydrogen atom. J

- In forming dyestuffs-in accordance with this invention the quaternarysalts employed may be.

for example, alkyl-or aralkyl-chlorides, bromides, iodides,.sulphates orperchlorates. Pref-- erably, however, the quaternary salts employed arealkyior aralkyl-p-toluene sulphonates, e. g. methyl or ethyl-p-toiuenesulph'onate.

In carrying out the process for the production of the dyestuils, it isnot necessary to isolate the quaternary salts of the two reactants. Thusby condensing a dyestuif intermediate of the general vl ormula 111 abovewith a heterocyclic nitrogen compound containing a methyl, a mono-substituted methyl or an amino group in the a-or 1-- position to the nitrogenatom. in the presence of a sumciency of alkyl or aralkyl salt to convertboth compounds to quaternary salts.-the reaction may beeflected in onestage. A particularly convenient method is to employ an alkyl or aralkyl-p-toluene sulphonate and to eilect the re-;

action by fusing together the dyestufl intermediateof the generalFormula III, the heterocyclic nitrogen compound containing the reactivegroupand the alkyl or aralkyl-p-toluene sulphonate.

Preferably. in the production of dyestuifs according to this invention,the condensation :is completedin the presence oi. an acid binding agent,e. g. pyridine, piperidine, triethylamine, sodium acetate or sodiumcarbonate. I 3

In naming the dyestuffs produced .according to this invention which havethe general Formula IV, they are regarded as trimethine cyanines inwhich one or more methine groups are replaced by nitrogen. This issignified in the name of the compound by the introduction of the term"az" preceding the word trimethine, the position of the a: group orgroups being indicated by a figure relating it to the heterocyclic ringto which it' isdirectly attached.

The following examples illustrate the tion:

inven- ExmLxI N(1-benzthiazolul) -dcetimino ethyl ether 37 gms. ofl-aminobenzthiazole and 50 gms. of. ethyl ortho acetate were mixedtogether and Preparation of Calls CHs heated for fifteen minutes under areflux .con-.

l-methyl benzselenazole and 4.00 gms. of ethylp-t'oluene sulphonate wasfused for three hours at 140-150" C. 20 cos. of pyridine were then addedto the mixture and the mixture boiled forhalf-an-hour. The mixture wasthen poured into potassium iodide solution and the precipitated dyestuifremoved by filtration; On boiling out the product with methyl alcoholand-removing impurities, the desired dyestui! was obtained as a reddishbrown powder, melting at 2.78 C.

The corresponding- .2:2'-dimethyl -8-methyl-7-az-trimethine-thiaselenacyanine bromide may be prepared by a similarmethod using-methyI-P- toluene sulphonate. It is a brown solid meltingat 252.C.-'

ExAurLaIII Preparation of2.1'-dimethyl-8-me'thill-7-dz-trimethine-thidquinocuanineiodide J I/\CH| I A mixture of 2,04 gms. of N(1-benzthiazolyl)- acetimino ethyleth'en- 3.72 gms. of methyl-ptoluene sulphonate andil.43 gms. ofquinaldine was fused for three hours at 130 to 140C. 20 cos. y orpyridinewere then added to the mixture and the mixture refluxed forhalf-an-hour. The mixture was then poured into potassium iodide solu-'tion, diluted with water, and filtered. The solid material, separated byfiltration was recrystallised from methyl alcohol and yielded thedesired dyestufl a a dark brown solid, melting at 210 C.

EXAMPLIIV Preparation of 2.2'-diethyl-8-m.ethyl-7-aztrimethine-thiacuanine iodide A mixture -of 10.1 ms. of N(1-benzthiazolyl)- acetimino ethyl ether, 7.5 ms. of l-methylbenzthiazole and 20gms. of 'ethyl-p-toluene sulphonate was fused for three hours at to C.100 .ccs. of pyridine was then added and the mixture was warmed on awater. bath and then refluxed for half-an hour. The mixture was thenpoured into potassium iodide solution and the precipitated dyestuflseparated by filtration. On recrystallisation the product was obtainedas a reddye, melting at 206 C.

The corresponding 2.2Gdimethyl-8-methyl-7- az-trimethine-thiacyanineiodide may be prepared by a similar method, using methy'l-p-toluenesulphonate. vIt is a red solid, melting at 276 C. i r ExsuruvPreparation of 2.Z'-dimethul-8-methvl-7.7'-diaz-trimethine-thiacyanineiodide c"-N=c-N%c I banner 7 A mixture of 2.0 gms. oiN-(l-benzthiazolyhacetimino ethyl ether. 1.5 gms. oi l-aminobenzthiazoleand 3.72 gms. oi methyl-p-toluene sulphonate was fused for three hoursat 140 to 150.- C. cos. of pyridine were then added and the mixture wasrefluxed tor halt-an-hour. The mixture was then poured into potassiumiodide solution whereupon the dyestufl separated out. Onrecrystallisation from methyl alcohol, the product was obtained as alight brown solid melting at 268 C,

Exmu VI Preparation of 2.2'-dtmethfll-8-meth1 l-7-az-trimethinethiaoxacyantne iodide A mixture of 10.1 gms. of N-(l-benzthiazolyD-acetimino ethyl ether, 6.7 gms. of l-methyl benzoxazole and 18.6 gms. ofmethyl-p-toluene sulphonate was fused for three hours at 120-130 C. 100cos. of pyridine were then added and the mixture refluxed for an hour.The product was poured into potassium iodide solution whereupon a darkoil separated. This was decanted oil and dissolved in hot ethyl alcohol.On cooling, the desired dyestufl was precipitated. It was recrystallisedfrom ethyl alcohol solution and had a melting point-oi 145 C.

EXAIPLI VII Preparation of LliI-(I-benzoxazolyl) acetimino ethyl etherv8.5 gms. oi l-amino benzoxazole and 11.5 gms. of ethyl orthoacetate wereboiled together for 15 minutes. The alcohol formed in the reaction wasremoved by distillation at normal pressure and the residue was thendistilled at reduced pressure. The product was thus obtained as a paleyellow oil solidifying to colourless prisms and.

boiling at 164-166 C. at mm. pressure.

Exam: V111 Preparation of N-(I-p-naphthathiazolul) -acettmino ethylether The preparation was effected as inExample VII using 22 gms.2-amino-p-naphthathiazole and 25 gms. of ethyl ortho acetate. Theproduct consisted of a light yellow solid. melting at 60 C. and boilingat 246 C. at 25 mm. pressure.

Preparation of 2.2'-dimethzll-8-methul-7-az-triusing 14.8 gms. oil-amino benzthiazole and 18.6 gms. of ethyl ortho propionate. Theproduct consisted of a yellow oil boiling at 204 C. at 25 mm. pressure.'a

' Exmm: x

Preparation of N-1- (5 ethoxy benzt hiazolvl) acetimino ethyl etherOCaHl \C-N=C/ The preparation was eilected as in Example VII using 13gms. of 1-amino-5-ethoxy-benzthiazole and 11 gms. of ethyl orthoacetate. The product consisted of a light yellow oil boiling at 223 I C.at 25 mm. pressure.

EXAMPLE XI methine ozathiacyan-ine iodide CH1 27K;

The preparation was eflected as in Example VI using 10 gms. ofN-(-1-benzoxazoly1)-acetimino ethyl ether, 7.5 gms. of l-methyibenzthiazole and 18.6 gms. or methyl-p-toluene sulphonate. The dyestuflprecipitated out from the potassium iodide solutionand was obtained asred crytals melting above 250 C.

EXAMPLE Preparation of 2.2-dimeth11l-8-meth1 l-7-az-trimethinenaphthathiacyantne iodide HI CHI The preparation was efiected as inExample VI using 9.7 gms. of N-l-(fl-naphthathiazolyl) acetimino ethylether,.4.9 gms. of l-methyl-benzthiazole and 12.4 gms. otmethyl-p-toluene sulphonate. The dyestufl was obtained asred crystalsmelting at 247 C.

Exsmru: XIII Preparation of 2.2'-dimethyl-8-ethrl-7 oz trimethinethiacyanine iodide The preparation was efiected 'asin Example VI- using13 isms. N-(l-benzthiazolyl) propionimino ethyl ether, 8.4gms.-'1-methyl-benzthiazole and 21 gms. of methyl-p-toluene sulphonate.The dye was obtained as a red solid melting at 247 C.

EXAMPL: XIV

Preparation of the dyestui! of the formula:

02350 S S t The preparation was effected as in Example VI using 11.8gms. of N-1-(5-ethoxy benzthiazolyl) acetimino ethyl ether, 6.6 gms. of1methyl benzthiazole and 17 gms. of methyl-p-toluene sulphonate. The dyewas obtained as fluffy orange crystals melting at 164 C. 1 EXAMPLE XVPreparation of the dyestuff of the formula:

' The preparation wasleflected as in Example VI using 9.7 gms. ofN-l-(fl-naphthathiazolyl) acetimino ethyl ether, 4.7 gms. of quinaldineand 12.4 gins. of methyl-p-toluene sulphonate. The dye was obtained as abrown solid melting at 212 C. i The dyestufl's produced according to thepresent invention are sensitisers for gelatino-silver halide emulsions,e. g. silver chloride and silver bromide and silver iodo bromideemulsions.

1 What we claim is: 1. Process for the production of dyestuff inter- 2.Process according to claim 1 wherein the ortho ester employed isselected fromthe group consisting of the alkyl esters of ortho aceticacid and of higher homologues of ortho acetic acid.

3. Dyestuff intermediates of the general formula:

1 I= on-on ':N=o

. .where D1 is the residue of a heterocyclic coma pound of the type usedin cyanine dyes, n is selected from the group consisting of nought and 1and R1 and R2 are selected from the group consisting of alkyl, aryl andaralkyl groups.

4. A process for the production of dyestufl intermediates whichcomprises reacting one mol l of a heterocyclic nitrogen compound of thegeneral formula:

wherein D1 is the residue of a heterocyclic nitrogen compound of thetype used in the preparation of cyanine dyes and n is a number selectedfrom the group consisting of nought and 1, with one mol of an orthoester of a monocarboxylic acid taken from the group consisting of thealkyl,

esters of ortho acetic acid and the higher homologues of ortho aceticacid, by heating the reactants together in the absence of a basiccondensing agent so as to form 2 mols of a mono-, hydric alcohol and adyestufl intermediate of wherein D1 and n have the above significance.

5. A dyestufl intermediate of the formula which is a colorless oilhaving a boiling point of 0 Calls G-N=C 198 C. at- 29 mm. pressure.

pound of the type used in cyanine dyes, n is selected from the groupconsisting of nought and l and R1 and R2 are selected from the groupconsisting of alkyl, aryl and aralkyl groups by heating the reactantstogether in :the absence of a basic condensing agent So as to form 2mols of amonohydric alcohol and a dyestufi intermediate of the formula:

wherein D1, R1, R2 and n have the above si 6. A dyestufl intermediate ofthe formula which is a pale yellow oil solidifying to colorless prismsand boiling at 164-166 C. at 25 mm. pressure. '7. A dyestufiintermediate of whichis a yellow oil boiling at 204 C. at 25 mm.- r uthe formula J OHN DAVID KENDALL. DOUGLAS JAMES FRY.

